RSR13 modifies the affinity of hemoglobin for oxygen, causing more oxygen release at the tissues. Since radiation effectiveness is limited by lack of oxygen in tumors, this drug may improve the efficacy of radiation. This will be a phase 1 trial. Side effects and tolerance as well as the pharmacokinetic/pharmacodynamic (PK/PD) profile of multiple daily doses of RSR13 in patients undergoing palliative irradiation will be determined.